Device for placing sleeves on traveling articles

Abstract

The invention relates to a device for placing sleeves on traveling articles, said sleeves being cut from a continuous sheath passing over a sheath-opening shaper, first outer wheels serving to advance the sheath along the shaper, and second outer wheels being provided downstream from cutter means for the purpose of ejecting the cut-off sheath segment, said wheels being driven in rotation by associated electric motors controlled synchronously by a virtual-shaft common electronic programmer. In accordance with the invention, the programmer is arranged to determine a continuous profile of speed variation for the associated electric motors, said profiles being bell-shaped and having a common end segment in which the profiles coincide, this corresponding to the motors having identical speeds, the length of the common end segment being selected so that the sheath is advanced beyond the point of tangential contact with the second wheels so that said sheath is pinched by said second wheels prior to being held stationary for the cutting and ejection pass.

What is claimed is: 
     
       1. A device for placing sleeves on traveling articles,
 said sleeves being cut from a continuous sheath passing over a sheath-opening shaper; 
 which shaper is held floating between first outer wheels and backing wheels having parallel axes carried by said shaper; 
 said first wheels serving to cause the sheath to advance along the shaper up to and beyond cutter means; 
 second outer wheels being provided downstream from the cutter means to eject each cut-off sheath segment onto an article located vertically below the shaper as a result of said article passing a cell; 
 said first wheel is rotatably driven by a first electric motor and said second wheel is rotatably driven by a second electric motor, wherein the first and second electric motors are controlled synchronously by a virtual-shaft common electronic programmer; 
 wherein the electronic programmer varies the speeds of the first and second electric motors in a accordance with a first and second continuous profile, respectively; 
 said first and second continuous profiles being bell-shaped curves that define the speed of the first and second electric motors, respectively, and having a common end segment in which the profiles coincide, which corresponds to the speeds of the of the first and second electric motors being identical; 
 wherein the length of said common end segment is selected so that the sheath is advanced beyond the point of tangential contact with the second wheels in such a manner that said sheath is pinched by said second wheels prior to being held stationary for the cutting and ejection pass. 
 
     
     
       2. The sleeve-placing device according to  claim 1 , wherein the virtual-shaft common electronic programmer includes at least one controlling electronic card associated with the first and second electric motors for driving the first and second wheels, the controlling electronic card being programmed such that the length of the common end segment that corresponds to the variations in the speeds of the first and second electric motors as a function of the angular positions of their respective virtual shafts, is directly representative of a predetermined distance between the point of tangential contact and the free edge of the sheath at the time said sheath is being held stationary for the cutting and ejection pass. 
     
     
       3. The sleeve-placing device according to  claim 2 , wherein the predetermined distance is also established when the sleeve-placing device is stopped, and remains frozen throughout the period said device is not in operation. 
     
     
       4. The sleeve-placing device according to  claim 2 , wherein the predetermined distance between the point of tangential contact and the free edge of the sheath lies essentially in the range 0.5 mm to 3 mm, and is preferably close to 1 mm. 
     
     
       5. The sleeve-placing device according to  claim 1 , wherein the second wheels are mounted on respective supports that are adjustable in position in the direction of the axis of the shaper, so as to adjust the distance between the point of tangential contact and the free edge of the sheath at the time said sheath is being held stationary for the cutting and ejection pass. 
     
     
       6. The sleeve-placing device according to  claim 1 , wherein the shaper has a smooth-walled downstream end, and the sheath is then pinched, at the time said sheath is being held stationary for the cutting and ejection pass, between the second wheels and said smooth wall. 
     
     
       7. The sleeve-placing device according to  claim 1 , wherein the shaper is fitted at its downstream end with backing wheels, and the sheath is then pinched, at the time said sheath is being held stationary for the cutting and ejection pass, between the second wheels and the associated backing wheels. 
     
     
       8. The sleeve-placing device according to  claim 7 , wherein the second wheels and the associated backing wheels have axes that slide in a common plane perpendicular to the axis of the shaper.